Sunday, April 27, 2008

The heart is a muscular organ a little larger than your fist weighing between 7 and 15 ounces (200 to 425 grams). It is responsible for pumping blood through the blood vessels by repeated, rhythmic contractions. The average heart beats 100,000 times per day pumping about 2,000 gallons (7,571 liters) of blood. The average human heart beating at 72 BPM (beats per minute), will beat approximately 2.5 billion times during a lifetime of 66 years.

The heart is usually situated in the middle of the thorax with the largest part of the heart slightly offset to the left underneath the breastbone or sternum and is surrounded by the lungs. The sac enclosing the heart is known as the pericardium.

The heart consists of the following parts:Aorta: It is the largest artery and carries oxygenated blood from the heart to the rest of the body.Superior Vena Cava: Deoxygenated blood from the upper parts of the body returns to the heart through the superior vena cava.Inferior Vena Cava: Deoxygenated blood from the lower parts of the body returns to the heart through the inferior vena cava.Pulmonary Veins: They carry oxygenated blood from the lungs back to the heart.Pulmonary Arteries: They carry blood from the heart to the lungs to pick up oxygen.Right Atrium: It collects deoxygenated blood returning from the body (through the vena cavas) and then forces it into the right ventricle through the tricuspid valve.Right Ventricle: It collects deoxygenated blood from the right atrium and then forces it into the lungs through the pulmonary valve.Left Atrium: It collects oxygenated blood returning from the lungs and then forces it into the left ventricle through the mitral valve.Left Ventricle: It is the largest and the strongest chamber in the heart. It pushes blood through the aortic valve and into the body.

HOW DOES THE HEART FUNCTION?

The right side of the heart collects de-oxygenated blood from the body into the right atrium and then via the right ventricle pumps it into the lungs so that carbon dioxide can be dropped off and oxygen picked up.

The left side of the heart collects oxygenated blood from the lungs into the left atrium. From the left atrium the blood moves to the left ventricle which pumps it out to supply oxygen to the body.